Added a couple of comments to the interface of traincascade.cpp in order to tell user about the usage of traincascade.cpp file and to learn how Github submitting works

apps/traincascade/traincascade.cpp

@@ -4,6 +4,11 @@
 using namespace std;
 using namespace cv;
 
+/*
+traincascade.cpp is the source file of the program used for cascade training.
+User has to provide training input in form of posotive and negative training images,
+and other data related to training in form of command line argument.
+*/
 int main( int argc, char* argv[] )
 {
     CvCascadeClassifier classifier;